1. Field of the Invention
The present invention relates to a marine riser connector. The invention has been found to be particularly useful in the connection of riser sections in a long string of low pressure service pipe between a floating vessel, such as, for example, a semisubmersible rig, and the ocean bottom, and hence, will be discussed with particular reference thereto. However, the invention is also applicable to other types of risers requiring sealing and high resistance to structural yield as the result of stress oscillation.
2. Description of the Prior Art
When floating drilling rigs, such as, for example, semisubmersible rigs, are operating in deep water, such as, for example, more than 300 feet of water, to drill a well, there are many problems associated with the design of marine risers connecting the drilling rig at the surface to the well located at the ocean bottom. The requirements of marine risers used with a floating drilling rig differ from those of risers used with a fixed platform drilling rig due to the moving point of connection at the surface for the riser for a floating drilling rig, both types having a rigid bottom connection at the ocean floor.
For a floating drilling rig, the well is completed at the mudline. Mudline completion is essential where floating drilling rigs are used, otherwise, there would be an open hole between the ocean floor and the floating vessel with the potential that the floating vessel would have to move off the hole, thereby leaving a hazard for pollution. Additionally, the weight of a riser adapted for high pressure service, if the well was not completed at the mudline, would be prohibitive to transport and support. Blowout preventers are, therefore, located at the wellhead, rather than on the rig, allowing the use of a low pressure riser system to connect the wellhead with the drilling vessel. The low pressure riser system is subject to a pressure differential between the static head of the water surrounding the riser and the drilling mud used to resist pressure in the well. To control the well, choke and kill lines must be strung externally to the drilling portion of the riser and as part of the riser and used in combination with drill pipe located inside the drilling portion of the riser. The riser system is, therefore, a series of sets of pipe sections connected at two common connection points to other sets of similar pipe sections, forming a continuous, fluid tight set of flow conduits from the ocean bottom to a floating platform.
Because of the large distances between the floating drilling rig and the mudline wellhead and because of the movement of the rig, such a riser system and the individual sections thereof will tend to cyclically bend, even though riser tensioners and other structures are provided to minimize the load cycles and degree of bend. Fatigue failure has been experienced by riser connectors between such riser sections as the result of such movement. See, Petroleum Engineer, October, 1974, Pages 36-46; Petroleum Engineer, Nov. 15, 1974, Pages 68-74; Petroleum Engineer, December, 1974, Pages 52-65; Petroleum Engineer, January, 1975, Pages 52-60; Petroleum Engineer, February, 1975, Pages 10-17; Petroleum Engineer, March, 1975, Pages 52-67; and Transactions of the Fortieth Annual Meeting of the Society of Petroleum Engineers of AIME, Paper SPE 1220.
Several types of pipe and tool joints have been known and used before, and typical examples thereof are shown in:
Composite Catalog of Oilfield Equipment and Services, 1974-75, Vol. 3, Pages 3984, 4260-64, 4987, published by World Oil; PA1 Composite Catalog of Oilfield Equipment and Services, 1974-75, Vol. 2, Page 1913, published by World Oil; PA1 Composite Catalog of Oilfield Equipment and Services, 1974-75, Vol. 1, Pages 1138A-1138B, 1635-38 published by World Oil; PA1 Vetco General Catalog, 1974-75, Pages 5186-89,5204; PA1 Composite Catalog of Oilfield Equipment and Services, 1972-73, Vol. 3, Pages 3192, 3284, 3286, 3318-19, 3326, 3692, 3694, 3912, 3914-15, 4379, 4509, 4520-23, 4529-32, 4660, published by World Oil; PA1 Rucker Catalog of Pressure Control Equipment Motion Compensation and Tension Control Systems, Page 4455; PA1 General Catalog OCT Wellhead Equipment 1974-75, Page 1954; PA1 O.C.T. Flow Fittings and Related Equipment, Page 25; PA1 Composite Catalog of Oilfield and Equipment Services, 1972-73, Vol. 2, Pages 1856, 2246, 2416, 2490, 2581, 3110, published by World Oil; PA1 Composite Catalog of Oilfield and Equipment Services, 1970-71, Vol. 3, Pages 3514, 3600-02, 3864, 4156-58, 4667-72, 4824, 4828-32, 4885-89, published by World Oil; PA1 Composite Catalog of Oilfield and Equipment Services, 1970-71, Vol. 2, Page 2255, published by World Oil; PA1 Composite Catalog of Oilfield and Equipment Services, 1970-71, Vol. 1, Pages 245, 270, 756-57, 871, 992, 1821, published by World Oil; PA1 Armco National Oil Field Products Composite Catalog, 1974-75, Page 3725; PA1 Regan Forge & Engineering Company Catalog, Pages 4156-58; PA1 Vetco Catalog, Pages 5196-98; PA1 3,853,338--issued Dec. 10, 1974, to William W. Wilson PA1 3,853,339--issued Dec. 10, 1974, to William W. Wilson PA1 3,827,728--issued Aug. 6, 1974, to J. H. Hynes; PA1 3,844,589--issued Oct. 29, 1974, to G. E. Bram; PA1 3,838,873--issued Oct. 1, 1974, to S. J. Gilbert; PA1 3,844,585--issued Oct. 29, 1974, to R. E. Sands, et al; PA1 2,825,585--issued Mar. 4, 1958, to C. L. Griffin; PA1 3,754,609--issued Aug. 28, 1973, to W. R. Garrett; PA1 2,636,753--issued Apr. 28, 1953, to C. L. Griffin; PA1 2,982,355--issued May 2, 1961, to O. N. Rodgers; PA1 3,345,084--issued Oct. 3, 1967, to J. W. E. Hanes, et al; PA1 3,345,085--issued Oct. 3, 1967, to J. W. E. Hanes; PA1 3,098,667--issued July 23, 1963, to E. C. Greenwood; PA1 2,924,434--issued Feb. 2, 1960, to R. R. Potter, et al; PA1 1,539,287--issued May 26, 1925, to R. A. Wilson; PA1 1,605,314--issued Nov. 2, 1926, to R. A. Wilson; PA1 1,507,877--issued Sept. 9, 1924, to R. A. Wilson; PA1 1,605,315--issued Nov. 2, 1926, to R. A. Wilson; PA1 1,614,815--issued Jan. 18, 1927, to R. A. Wilson; PA1 1,629,058--issued May 17, 1927, to R. A. Wilson; PA1 1,637,628--issued Aug. 2, 1927, to Edwin C. Weisgerber; PA1 1,668,921--issued May 8, 1928, to P. Miks; PA1 1,645,032--issued Oct. 11, 1927, to R. A. Wilson; PA1 1,671,458--issued May 29, 1928, to R. A. Wilson; PA1 2,049,290--issued July 28, 1936, to E. Burns, et al; PA1 2,107,716--issued Feb. 8, 1938, to J. C. Singleton; PA1 2,228,243--issued Jan. 14, 1941, to R. C. Baker; PA1 3,421,580--issued Jan. 14, 1969, to J. H. Fowler, et al; PA1 3,442,536--issued May 6, 1969, to J. H. Fowler; PA1 3,224,799--issued Dec. 21, 1965, to T. L. Blose, et al; PA1 3,114,566--issued Dec. 17, 1963, to C. J. Coberly, et al; PA1 2,931,670--issued Apr. 5, 1960, to W. L. Church; PA1 2,907,589--issued Oct. 6, 1959, to G. S. Knox; PA1 1,469,009--issued Sept. 25, 1923, to C. Overstreet; PA1 Canadian Pat. No. 469,786--issued Nov. 28, 1950, to Louis Edmund Edwards. PA1 2,773,707--issued Dec. 11, 1956, to J. Fraser; PA1 1,080,675--issued Dec. 9, 1913, to P. Berg; PA1 1,019,558--issued Mar. 5, 1912, to K. H. Thompson; PA1 2,283,974--issued May 26, 1942, to S. V. Dillon; PA1 1,910,161--issued May 23, 1933, to G. G. Harrington; PA1 725,337--issued Apr. 14, 1903, to C. H. Haeseler; PA1 Re.21,234--issued Oct. 17, 1939, to W. L. Church; and PA1 2,645,438--issued July 14, 1953, to I. Kalikow; PA1 183,891--issued Oct. 31, 1876, to J. G. L. Boettcher; PA1 314,783--issued Mar. 31, 1885, to G. W. Beebe; PA1 906,217--issued Dec. 8, 1908, to E. G. Gaylord; PA1 1,008,551--issued Nov. 14, 1911, to W. A. Lorenz; PA1 1,311,145--issued July 22, 1919, to W. Zeindler, et al; PA1 222,713--issued Dec. 15, 1879, to W. A. Lawson; PA1 2,039,787--issued May 5, 1936, to N. O. Fogelstrom; PA1 2,066,956--issued Jan. 5, 1937, to G. H. Williams; PA1 2,627,429--issued Feb. 3, 1953, to H. C. Engelman; PA1 290,663--issued Dec. 25, 1883, to D. S. Blue; PA1 2,539,456--issued Jan. 30, 1951, to G. Meier; PA1 3,275,354--issued Sept. 27, 1966, to W. N. Sutliff, et al; PA1 3,116,942--issued Jan. 7, 1964, to W. Morello, Jr.; PA1 2,828,662--issued Apr. 1, 1958, to J. A. Antal; PA1 Re.13,222--issued Mar. 28, 1911, to C. H. Chapman; PA1 British Pat. No. 15,375--issued June 28, 1897, to Craig; PA1 Swiss Pat. No. 373,608--issued Jan. 15, 1964, to Auguste Ernest Chevalley; and PA1 Canadian Pat. No. 642,982--issued June 19, 1962, to Harl Remington. PA1 3,848,905--issued Nov. 19, 1974, to V. S. Hammer, et al; PA1 2,295,716--issued Sept. 15, 1942, to O. C. Cox; PA1 787,154--issued Apr. 11, 1905, to J. J. Delehant; PA1 774,667--issued Nov. 8, 1904, to W. S. Houser; PA1 3,014,740--issued Dec. 26, 1961, to J. D. Bogsian, et al; PA1 3,851,901--issued Dec. 3, 1974, to Cecil M. Sills; PA1 3,827,732--issued Aug. 6, 1974, to M. Noguchi, et al; PA1 3,480,300--issued Nov. 25, 1969, to W. C. Jeffery, et al; PA1 2,684,860--issued July 27, 1954, to A. W. Rafferty; PA1 112,958--issued Mar. 21, 1871, to J. B. Ramp; PA1 633,324--issued Sept. 19, 1899, to C. Luke; PA1 1,034,781--issued Aug. 6, 1912, to J. Gapp; PA1 1,853,411--issued Apr. 12, 1932, to H. L. Gentry, et al; and PA1 1,866,863--issued July 12, 1932, to L. L. Richardson. PA1 Great Britain Pat. No. 1,109,623--issued June 15, 1966, to Ritter Pfandler Corporation.
U.S. Pat. Nos.: PA0 U.S. Pat. Nos.: PA0 U.S. Pat. Nos.:
None of these, however, teaches a quick stabbing riser connector for long riser strings connecting choke and kill lines and pipe sections through the use of a male member, a female member with a nut thereabout, the members and nut being preloaded through the use of multiple broken threads on the male member and the nut. They, therefore, do not solve the problem of failure of a nut type riser connection because of fatigue.
Several other types of connection devices have been known and used before, and typical examples thereof outside the riser string or tool coupling art and not employing nuts are shown in:
None of these devices, however, teaches the use of a male and female member with a nut, the members in compression and the nut in tension.
Several types of pipe and equipment couplings using a male and female member in conjunction with one or more nuts, some including lugs, have been known and used before, and typical examples thereof are shown in:
None of these, however, show a riser joint capable of high prestress on mating shoulders.